Coil pack replacement - NB
by Chess Martin
You should be able to swap out a '99 Miata coil pack in about 30-45 minutes
the first time with a minimum of mechanical expertise, or even inclination in
First, get the tubes and wires out of your way.
- Unhook the negative battery cable and push the brake pedal once to discharge
any residual power.
- The sparkplug wires are bit tough to pull off...I used channel-lock pliers
to gently pull them off of the coil. Note the order of the wires (4,1,2,3).
If you have the blue NKGs, they are labled with numbers.
- The wires across the top of the coil and the plastic tubing can be removed
by pinching the underside of the plastic clips that hold them on (I used needlenose
pliers, but that only worked marginally).
- The metal tube (you'll see as it's clearly in your way) can be unhooked
on the left end and propped out of the way after removing two bolts in the
Next, remove the coil.
- Looking from driver's side, note the wire going from the coil pack to the
engine block. This can be pulled off by squeezing the flat tab while pulling
- Remove the three 12mm bolts that hold the coil pack on with a combo of
a 12mm socket with extension and a 12mm wrench (preferably angled). (I have
the most problem with the third bolt located at the bottom of the coil pack.
There is not enough room in there. I position myself on the passenger side
and I put a socket wrench with 12mm sockets on the other side. I guide the
end of the socket with my left hand and with my right hand on the socket ,
I push down. Its in there so tight but finally gave in.)
- Now that the coil pack is loose, you should be able to manuever it in such
a way as to remove the two wire sets from the back. This is where I struggled
- You see the tabs that look like they should be pressed in? Push them fairly
hard with your index finger while pulling them off with your middle finger
and thumb (WATCH YOUR KNUCKLES!) (Its easier to pull the coil pack up and
into the top of the engine. With the connectors on top, push the tab with
a screwdriver and with another screwdriver, carefully pry upward the male
connector. In fact, I find this technique of disconnecting plastic connectors
with tabs a lot easier than using your hands).
- Note that one of these wires has a blue wrap, and that the side of the
coil it goes on has a blue dot...making them pretty much idiot proof.
- Now that the old coil is off, note the rubber bushing on the bottom that
is not on the new part. If you can get this off without damaging it and can
get it on the new coil pack, you are a better person than I am. (I was able
to remove the bushing by loosening it with a small screwdriver. First remove
the center piece. Place the flat end of the screwdriver on the edge of the
bushing and carefully hit it with a hammer. You can then pry it off. Put it
on the new coil pack).
- I just put the new coil on with the two top bolts and it seems very secure.
Put on the new coil in the logical reverse order...back wires, then bolts,
then plug wires, then everything else. Hook the battery back up and take her
for a spin. If it's like mine, she'll idle a bit strange for the first 10 minutes
Good luck, and watch those knuckles.